Depending on the version of ubuntu you may come accross this error when trying to install bullet or mesa libs

Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

This is nearly always caused by the Ubuntu updater being active in the background, which is the other process it's asking about, and doing exactly what its designed to. Unfortunately while its doing it, there's nothing you can really do, it has a priority over the directories while its in progress.

On the 1st run, the updater is downloading and installing any updates, so you just have to wait for it. Once its done (this can take up to an hour), you can usually go to your system updater via the System->Administration->Software Updater and switch off the auto updates.
Annoyingly you can't switch them off if an update has alrady started.

Brian BeukenLecturer in Game Programming at Breda University of Applied Sciences.
Author of The Fundamentals of C/C++ Game Programming: Using Target-based Development on SBC's